Since the oyster and other bivalve industries have shifted heavily toward use of triploids because non-reproductive oysters enhance production (Nell, 2002)âalso a welcome trend for minimizing impacts on natural populations, as discussed belowâbreeding programs â¦ The spermatozoa of bivalves are unusual in that they have two tails. Chapter 3 Reproductive investment of the bivalves Cerastoderma edule 47 (L.) and Mya arenaria L. in the Dutch Wadden Sea (in preparation) Chapter 4 Habitat related growth and reproductive investment in estuarine 65 waters, illustrated for the tellinid bivalve Macoma â¦ Spermatophores are capsules created by the males which contains sperm which is transferred during copulation. The gills have evolved into ctenidia, specialised organs for feeding and breathing. Clams and oysters are protandrous (begin as males and later develop into females) iii. Bivalve Reproduction Lecture Notes I. The nervous system is made up of three pairs of ganglia. The simplest mollusk reproductive system relies on external fertilization but there are more complex variations. Bivalve anatomy as well as their reproductive behavior provide a link between more simplistic animals and more complex, like humans. They are both male and female during their lifetime ii. The digestive system of a bivalve is fairly simple, similar to a wormâs, a far cry from the human digestive system. We will explore a little about bivalves here. All produce eggs, from which may emerge larvae, or miniature adults. A male's reproductive system consists of a meter long arm called the hectocotylus that it uses to insert it's spermatophores into the female's oviduct. Reproductive System. Most bivalves bury themselves in sediment on the seabed, while others lie on the sea floor or attach themselves to rocks or other hard surfaces. The morphological changes in the oviduct and oviducal gland observed throughout the reproductive cycle in O. vulgaris mirror progesterone and estradiol fluctuations, suggesting that both steroids might work in synergy to sustain the growth and differentiation of the female reproductive system in this species (Di Cosmo et al., 2001). These innervate the musculature, mantle, viscera, ctenidia, and siphons. The shell of a bivalve is composed of calcium carbonate, and consists of two, usually similar, parts called valves. This synchronized spawning results in the release of large amounts of both types of gametes into the â¦ The eggs hatch into veligers that live among and eat other plankton. General Characteristics a. Bivalve mollusks, such as clams, oysters and scallops have unique reproductive biology, in that they are all hermaphroditic i. Bivalve eggs and sperm are usually released into the water, where fertilization takes place. Weâll go over the different parts of the â¦ Bivalve ova are generally small and many species synchronize their release of reproductive material. -Bivalves usually require both males and females to reproduce, although some species individuals either have the organs of both sexes or start out as males and later become females. The full text of this article hosted at iucr.org is unavailable due to technical difficulties. The scrotum is a sac of skin that contains several important parts of the male reproductive system. The bivalve foot is modified as a powerful digging tool in many groups, while in those that live a permanently attached life (e.g., oysters), it is very reduced.